The present disclosure relates to a data storage device. More particularly, the disclosure relates to a data storage device including a mechanism for removing contaminants from emission surfaces of electron emitters within the device.
Researchers have continually attempted to increase the storage density and reduce the cost of data storage devices such as magnetic hard-drives, optical drives, and dynamic random access memory (DRAM). Recently, semiconductor-based electron sources have been developed that can be used in storage devices and which may avoid the difficulties noted above. An example of such a data storage device is described in U.S. Pat. No. 5,557,596. The device described in that patent includes multiple electron emitters having electron emission surfaces that face a storage medium. During write operations, the electron sources bombard the storage medium with relatively high intensity electron beams. During read operations, the electron sources bombard the storage medium with relatively low intensity electron beams. Such a device provides advantageous results. For instance, the size of storage bits in such devices may be reduced by decreasing the electron beam diameter, thereby increasing storage density and capacity and decreasing storage cost.
During fabrication, various contaminants from the ambient air can form on the electron emission surfaces of the data storage device. Such contaminants include various materials containing oxygen, nitrogen, and/or carbon. Perhaps most problematic of these is carbonaceous materials such as hydrocarbons. The formation of contaminants is disadvantageous in that their presence adversely affects operation of the electron emitters. For instance, the presence of contaminants increases electron scattering. In addition, where the electron emitters comprise field (i.e., tip) emitters, the work function of the emitters can be decreased, lowering the potential needed to emit electron beams from the emitters and thereby raising the currents substantially. This phenomenon makes it more difficult to control operation of the emitters in that the magnitude of the electron beams emitted from the emitters may be greater than desired, therefore increasing the opportunity for misreading and/or miswriting to a storage medium of the device. Removing these contaminants from the atmosphere to prevent their deposition on the electron emission surfaces during fabrication is difficult, if not impossible.
In addition to contaminants present in the ambient air during fabrication, further contaminants can be deposited on the emission surfaces of the electron emitters. For example, if the storage medium of the device is partially decomposed, or if contaminants on the surface are desorbed, during read and/or write operations, volatile components can be released that will settle on the electron emission surfaces. Like the airborne contaminants referenced above, these contaminants can similarly result in electron scattering and may significantly change emitter operational characteristics.
From the foregoing, it can be appreciated that it would be desirable to have a data storage device that employs a mechanism to remove contaminants from the emission surfaces of the electron emitters contained within the device.
The present disclosure relates to a data storage device. The data storage device comprises a closed interior space containing a noble gas, a plurality of electron emitters having emission surfaces exposed within the interior space, the electron emitters adapted to emit electron beams, and a storage medium contained within the interior space in proximity to the electron emitters, the storage medium having a plurality of storage areas that are capable of at least two distinct states that represent data, the state of the storage areas being changeable in response to bombardment by electron beams emitted by the electron emitters.
In addition, the present disclosure relates to a method for removing contaminants from an electron emission surface of an electron emitter of a data storage device. The method comprises the steps of providing a noble gas within an interior space of the data storage device to which the electron emission surface is exposed, exciting atoms within the gas by impacting them with an electron beam emitted by the electron emitter, wherein the atoms of the gas are ionized by impact with the electron beam and accelerated toward the emission surface to sputter remove the contaminants from the emission surface.
In preferred arrangements, the noble gas used in the device and method comprises neon gas.
The features and advantages of the invention will become apparent upon reading the following specification, when taken in conjunction with the accompanying drawings.